The invention concerns N-(chlorocarbonyloxy)-5-norbornene-2,3-dicarboximide I, processes for its production as well as its use. The compound I is new. It represents an important intermediate product for the manufacture of non-symmetrical carbonates and activated polymeric carriers. The utility of the present invention lies in the pharmaceutical and chemical industries, as well as in biotechnology.
Chloroformic acid esters are known to be compounds of great preparative significance. For the production from phosgene and the hydroxyl compounds, three processes are employed. In the most important process, phosgene is reacted directly with the alcohols (B. Roge, Liebigs Ann. Chem. 205, 227 (1880); Houben-Weyl, 4. Aufl. (1952), Bd. 8, S. 101 bis 102; US-PS 2476 637). For this purpose, either liquid phosgene or a phosgene in an inert organic solvent (toluene) is provided, and the alcohol is added dropwise. (W. Hentschel, Chem. Bericht 18, 1177 [1885]) or the reverse, phosgene is lead through cooled alcohol. (C. Hamilton, C. Sly, Amer. Chem. Soc. 47, 436 [1925]). According to another technique, one works with tertiary amines, and the hydrogen chloride produced during the reaction is supposed to be collected. As tertiary amine, e.g., dimethylaniline or pyridine is used. These processes are suitable mainly for the production of aromatic chloroformic acid ester. In other techniques for the aromatic chloroformic acid esters, alkali phenolates are mentioned for hydrogen chloride binding with the reaction with phosgene. These techniques follow in inert solvents (K. V. Anwers, W. Scheich, Chem. Ber. 54, 1969 [1921]), or even in aqueous organic solvent systems (E. Barrat, A. Morel, Comptes Rendus Hebdomadaires des Seances de l'Academie des Sciences 128, 1578 [1899]).
The chloroformic acid esters of 9-fluorenyl-methanol, of pentachlorophenol, of benzotriazol and of N-hydroxysuccinimide are important as initial products for protective groups in the synthesis of peptide (A. Paquet, Can. J. Chem. 60, 976 [1982]). However, the obtained chloroformic acid esters, limited by their low hydrolysis stability or too low aminolysis velocity are not advantageously useful. A plurality of symmetrical carbonates is moreover, known which are employed for the introduction of urethane protective groups in amino acids. The tert.-butyloxycarbonyl-(BOC)-group represents, in addition to the benzyloxycarbonyl-(Z)-group, the most frequently employed protected group in the peptide synthesis. In order to avoid the disadvantages of high toxicity and explosion tendency possessed by the previously mainly employed BOC-introduction reagents tert.butyloxycarbonyloxide (Schwyzer, R., Sieber, P. and Keppler, H., Helv. Chim. Acta 42, 2622 [1962]), new introduction reagents have been developed in great number, such as tert.-butyl-4-,6-dimethylpyrimidyl-2-thiol-carbonate (Hagasawa, T., Kuriowa, K., Nerite, K. and Isowa, Y., Bull Chem. Soc. [Jap.] 46, 1269 [1973], and A. C. McGregor, J. Amer. Chem Soc. 72, 6180 [1957]); tert.-butyloxycarbonyloxyimino-2-phenylacetonitrile (Itoch., H., Hagiwara, D. and Kamiya, T., Bull. Chem. Soc. [Jap.] 50, 718 [1977]; Tetrahedron Lett. 1975, 4393; N-(tert.butyloxycarbonyloxy)-phthalimide (Gross, N. and Bilk, L. Liebigs Ann. Chem. 725, 212 [1969]); N-(tert.-butyloxycarbonyloxy)-succinimide (Franket, M., Ledkeny, D., Gilon, C. and Wolamn, Y., Tetrahedron Lett. 1966, 4765; Gross, H. and Bilk, L., Liebigs. Ann. Chem. 725, 212 [1969], N-(tert.-butyloxycarbonyl)-1H-1,2,4-triazol (G. Bram, Tetrahedron Lett. 1973, 469), tert.-butyl-phenylcarbonate (Ragnarsson, U., Karlson, S. M., and Sandberg, B. E., Acta Ehcm. Scand. 26, 2550, [1972]; Org. Synth. 53, 25 [1973]); tert.-buty-S-quinolycarbonate (Rzesztotarska, B. and Wiejak, S., Liebigs Ann. Chem. 716, 216 [1968]; Rzesxtotarska, B., Wiejak, S. and Pawelozak, K., Org. Prep. Proc. Int. 5, 71 [1973]); tert.-butyl-2,4,5-trichlorophenylcarbonate (Broadbent, W., Morley I. S., and Stone, B. E., J. Chem. Soc. (C), 1967, 2632) and Di-tert.-butyl-dicarbonate (Tarbell, D. S., Yamamoto, Y. and Pope, B. M., Proc. Nat. Acad. Sci. USA 69, 730 [1972]; Org. Synth. 57, 45 [1977]; Moroder, L., Hallet, A., Wunsch, E., Keller, O. and Wersin, G., Hoppe-Seyloer's Z. Physiol. Chem. 357, 1651 [1976]).
In addition to these frequently employed protective groups, further significant protective groups are required for specific synthesis problems. In this connection, in recent years, mainly such compounds have been approved which can be split off under milder conditions. These include, e.g., the 9-fluoroenylmethyloxycarbonyl-group (Carpino, L., J. Amer. Chem. Soc. 92, 5748 [1970]), the methylsulfonylethoxycarbonyl-group (G. Tesser et al., Intern. J. Peptide Prot. Res. 7, 295 (1975) or 1-adamantyloxycarbonyl-protective group (E. Wunsch, L. Wackerle and L. Moroder, Hoppe-Seylers Z. Physiol. Chem. 357, 1647 [1976]). All of these last mentioned protective groups are usually introduced across substituted phenol or H-hydroxysuccinimide ester (M. Bodanszky, Y. S. Klausner and M. A. Ondetti in: Peptide Synthesis, 2nd ed., J. Wiley & Sons, N.Y., 1976, p. 32; H. Gross and L. Bilk, Liebigs Ann. Chem. 725, 212 [1969]; A. Paquet, Can. J. Chem. 57, 2775 [1979] and Can. J. Chem. 60 (8) [1982]).
The mentioned introduction reagents distinguish by the remarkably high yields of urethane-protected amino acids that are obtained. Their disadvantage, however, for the most part, is that with the majority of them, not only the synthesis of the starting material but also the manufacture of the introduction reagent, is connected with high preparative and technical expenditure and their storage stability is limited. Moreover, often the aminolysis velocity is limited.
Also known are so-called carrier-fixed reagents, which are employed during material transformation processes or analytical and preparative material separations. (A. Wisemann, ed., Handbood of Enzyme Chemistry, New York, 1975, D. R. Lowe: "An Introduction to Affinity Chromatography", Amsterdam, 1979.) The carrier-fixed system is composed of the polymeric matrix, the carrier, in which by means of covalent or adsorptive binding, the material with the desired specifc activity (ligands) are connected. Natural or synthetic compounds with determined chemical or biological activity are employed as ligands, e.g., enzyme as catalyst for material transformation, protein and peptide with the activity of lectines, inhibitors, antigens or antibodies, nucleic acids, polysaccharides, sugar-derivatives, among others. The polymers employed for the binding of the ligands are natural polysaccharides such as, e.g., cellulose, starch, dextrane, agarose and their derivatives, or synthetic, hydroxyl group-containing polymers such as mixed polymerizate of 2-hydroxylethylmethacrylate (Spheron) or phenol-formaldehyde condensate (Duolite) as well as amino group-containing polyers such as polyacrylamide, modified polysaccharide (e.g., AH-Sepharose) or even proteins.
The manner of forming covalent bindings between carriers and ligands exerts a substantial influence on the characteristics of the produced product, and is therefore always the subject of renewed investigations. Most frequently, the binding of peptide-like ligands follows across their accessible alpha- and epsilon-amino groups, although the possibility also exists for reaction of the carboxyl group or the SH group. Prerequisite for the binding of the ligands is the activation of the chemically slightly reactive hydroxyl groups of the carrier.
Of many possible activation methods the reaction of the polysaccharide into cyanate or imidocarbonate is mainly performed in practice by means of cyanogenbromide, although a series of disadvantages is attached to it (i.e., the reaction of the CNBr-activated carrier with amino groups leads to isourea derivatives which can maintain the character of weak ion exchangers; and high toxicity of the bromocyanogen and its hydrolysis products).
An activation of the hydroxyl groups has furthermore, been described with benzoquinone, divinyl sulfone, diepoxide, trichlorotriazine and other bifunctional reagents, as well as the oxidation of the hydroxyl groups into aldehyde functions by means of sodium periodate.
A promising alternative to the activation with bromocyanogen is seen in the reaction of polysaccharides with chloroformic acid esters.
In the case of the reaction of the chloroformic acid ethyl ester with cellulose (S. A. Barker, Carbohydr. Res. 17, 471 [1971]), the formation of trans-2,3-cyclical carbonate and O-ethoxycarbonyl functions has been described, which react with amino groups. The binding of several enzymes and the manufacture of immunoadsorbants is known. (C. H. Grey, Carbohydr. Res. 27, 235 [1973]; J. F. Kennedy, J. Immunol. Meth. 50, 57 [1982]).
The high toxicity and the extreme hydrolysis sensitivity of this chloroformic acid ester are the main disadvantages of this activation. Seen to be advantageous compared to the activation with bromocyanogen is the high stability of the noncharged urethane-compounds arising by means of reaction with amino functions. The usefulness of the method is clearly improved through insertion of more reactionable and more hydrolysis-resistant chloroformic acid esters, which are employed in peptide chemistry. The Sepharose, Spheron and cellulose carriers activated by means of chloroformic acid-p-nitrophenyl ester, chloroformic acid-N-hydroxysuccinimide ester or chloroformic acid-trichlorophenyl ester are stable in the dry state or in water-free dioxane. (J. Drobnik, Biotechnol. Bioeng. 24, 487 [1982]; M. Wilchek and T. Miron, Biochem. Internat. 4, 629 [1982]).
Characteristics that are decisive for the practical usefulness are the high chemical and storage stability of the activated carrier and of the chloroformic acid ester employed for the production. Whereas the stability of the previously described activated carriers has been satisfactory, not only chloroformic acid ethyl ester but also chloroformic acid-N-hydroxysuccinimide ester are difficultly handleable on account of their high hydrolysis sensitivity, particularly when they are supposed to be worked up in greater scale. Disadvantages of the chloroformic acid-phenyl ester derivatives exist in that the separation of the most poisonous phenols produced upon the reaction with amino functions is difficult, but must nevertheless follow very thoroughly since they frequently disturb the biological activity of the systems investigated. Accordingly, protracted washing of the manufactured carrier-fixed enzymes, among others, is necessary.
The methods useful for the immobilization of the most diverse ligands in polymeric carriers are described in reviews and monographs. (Chemical Analysis, Vol. 59, P. J. Elving and J. D. Winefordner, eds., New York, 1981; E. A. Hill, M. D. Hirtenstein, in Advances in Biotechnological Processes 1, pp. 31-66, New York, 1983.)